[sdiy] VCO Cap Switch
ijfritz at earthlink.net
Thu Jun 6 04:34:23 CEST 2002
At 10:00 PM 6/4/2002, Scott Bernardi wrote:
>The datasheet shows the LM319 spec'd at 36v max, same as a LM311.
True. But I found that to get full output swing I had to use a rather small
(750R - 1k) pullup resistor. In my TRI oscillators this caused the chip to
run quite hot, so I reduced the PS voltages. Tracking was then much
improved. For a SAW oscillator this isn't a big issue.
>The LM311 needs
>a pullup resistor also, doesn't it?
Not that I can see.
Another issue with the 319 is that there aren't any good application
schematics. I must say, I really don't know the proper way to connect the
ground pins. I just hooked them to the - supply, but this actually violates
one of the max ratings. May be this is why I had trouble with heating.
>I used the second comparator in the LM319 for the pulse output (sawtooth
>input and PWM input on the other).
A good plan.
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